Stepper Recipes

Below is a listing of stepper lithography recipes. Stepper 1 and Stepper 2 are i-line systems with good piece handling capabilities. Stepper 3 is a DUV (248nm) system. DUV resists do not work for i-line and i-line resists do not work for DUV. Based on your sample reflectivity, absorption (or whether or not you use an ARC layer), and surface topography the exposure time / focus offset parameters may vary. This listing is a guideline to get you started. The recipes are tabulated to give you the values of the key parameters you will need to establish your recipe. Underlayers such as LOL2000 or PMGI can be used on the stepper systems. See the underlayer datasheets for details. Post develop bakes (not listed) are used to make the resist more etch resistant and depend on subsequent processes. Care should be taken with post development bakes as resist reflow can occur. Unless otherwise noted, all exposures are done on flat, silicon wafers.

Parameters are indicated in separate tables for each stepper system. Multiply the exposure times by 0.30 (from the 6300 system) to get a starting exposure time for the GCA Autostep200 system. You will need to do a focus and/or exposure array to get optimal process parameters.

Positive Resist (GCA 6300)

Unless otherwise noted, bakes are on hot plates. For recipes with CEM, the CEM is spun on after the first resist bake, exposure is then done, and the CEM is rinsed off with DI water before the PEB. CEM generally improves resolution and process tolerance at the expense of higher exposure time.

Negative Resist (GCA 6300)

Unless otherwise noted, bakes are on hot plate. All flood exposures are done in broadband light using any contact aligner. Also, because the tone is negative, a shorter first exposure time will result in more undercut, which is desirable for single-layer lift-off processes. Under these conditions more develop time will also give more undercut.

Positive Resist (AutoStep 200)

Unless otherwise noted, bakes are on hot plates. For recipes with CEM, the CEM is spun on after the first resist bake, exposure is then done, and the CEM is rinsed off with DI water before the PEB. CEM generally improves resolution and process tolerance at the expense of higher exposure time.

NOTE: The bolded exposure times were found by multiplying the exposure times from the GCA 6300 system by 0.30. They should be sued as a starting point. You will need to do an exposure array to get precise times for the Autostep system. In general, the resolution achievable is ~ 100 nm smaller for the Autostep200 system.

Let sample sit in air for 20 minutes before PEB, step to 50°C for 60” first, then 115°C

Negative Resist (AutoStep 200)

Unless otherwise noted, bakes are on hot plate. All flood exposures are done in broadband light using any contact aligner. Also, because the tone is negative, a shorter first exposure time will result in more undercut, which is desirable for single-layer lift-off processes. Under these conditions more develop time will also give more undercut.

NOTE: The bolded exposure times were found by multiplying the exposure times from the GCA 6300 system by 0.30. They should be sued as a starting point. You will need to do an exposure array to get precise times for the Autostep system. In general, the resolution achievable is ~ 100 nm smaller for the Autostep200 system.

Positive Resist (ASML DUV)

Anti-reflective coatings are, in general, used for the ASML stepper. LOL2000 and PMGI can also be used. For AR2 coatings, spin coat at 3500rpm for a 670A thick coating. Bake at 220C for 60s on a hotplate. This AR coating is removed via oxygen plasma. RIE 5 parameters are 20sccm, 10mT, 100W for 40s. For DS-K101, spin at 5000rpm and bake at 185C for 60s. This AR coating develops away and undercuts in AZ300MIF. For isolated lines, this can cause them to lift-off. If undercut rate is too high, increase bake temperature.

Resist

Spin Cond.

Bake

Thickness

Exposure Dose(mj)

Focus Offset

PEB

Developer

Developer Time

Comments

UV6-0.7

3.5 krpm/30”

135°C/60”

630nm

17

-0.2

135°C/90”

AZ300MIF

45”

200nm dense line/space

NA 0.57, Sigma 0.75

Eo ~ 5.5mj

UV210-0.3

5.0 krpm/30”

135°C/60”

230nm

20

-0.1

135°C/90”

AZ300MIF

45"

150nm dense line/space

NA 0.63, Sigma_o 0.8, Sigma_i 0.5

UV210-0.3

3.0 krpm/30”

135°C/90”

260nm

85

-0.2

135°C/90”

AZ300MIF

80”

170nm isolated holes

NA 0.63, Sigma_o 0.8, Sigma_i 0.5

Negative Resist (ASML DUV)

Anti-reflective coatings are, in general, used for the ASML stepper. LOL2000 and PMGI can also be used. For AR2 coatings, spin coat at 3500rpm for a 670A thick coating. Bake at 220C for 60s on a hotplate. This AR coating is removed via oxygen plasma. RIE 5 parameters are 20sccm, 10mT, 100W for 40s. For DS-K101, spin at 5000rpm and bake at 185C for 60s. This AR coating develops away and undercuts in AZ300MIF. For isolated lines, this can cause them to lift-off. If undercut rate is too high, increase bake temperature.